Leiden Institute of Chemistry, Leiden University, PO Box 9502, Leiden 2300 RA, The Netherlands.
Cosine Measurement Systems, Oosteinde 36, Warmond 2361 HE, The Netherlands.
Nat Commun. 2016 Aug 24;7:12653. doi: 10.1038/ncomms12653.
Cathodic corrosion is a process that etches metal electrodes under cathodic polarization. This process is presumed to occur through anionic metallic reaction intermediates, but the exact nature of these intermediates and the onset potential of their formation is unknown. Here we determine the onset potential of cathodic corrosion on platinum electrodes. Electrodes are characterized electrochemically before and after cathodic polarization in 10 M sodium hydroxide, revealing that changes in the electrode surface start at an electrode potential of -1.3 V versus the normal hydrogen electrode. The value of this onset potential rules out previous hypotheses regarding the nature of cathodic corrosion. Scanning electron microscopy shows the formation of well-defined etch pits with a specific orientation, which match the voltammetric data and indicate a remarkable anisotropy in the cathodic etching process, favouring the creation of (100) sites. Such anisotropy is hypothesized to be due to surface charge-induced adsorption of electrolyte cations.
阴极腐蚀是一种在阴极极化下刻蚀金属电极的过程。据推测，该过程是通过阴离子金属反应中间体发生的，但这些中间体的确切性质和形成的起始电位尚不清楚。在这里，我们确定了铂电极上阴极腐蚀的起始电位。在 10M 氢氧化钠中对阴极极化前后的电极进行电化学表征，结果表明电极表面的变化始于相对于标准氢电极的-1.3V 电极电位。该起始电位值排除了先前关于阴极腐蚀性质的假设。扫描电子显微镜显示出具有特定取向的清晰定义的腐蚀坑的形成，这与伏安数据相匹配，并表明在阴极刻蚀过程中存在显著的各向异性，有利于（100）位的形成。这种各向异性被假设是由于表面电荷诱导的电解质阳离子吸附所致。
